Needled fibrous batting and method of making the same



H. w. coATEs 3,523,059

NEEDLED FIBROUS BATTING AND METHOD OF MAKING THE SAME Filed Aug. 25, 1967 INVENTOR Herbert W. Cootes United States Patent O 3,523,059 NEEDLED FIBROUS BATTING AND METHOD OF MAKING THE SAME Herbert W. Coates, Charlotte, N.C., assignor to Celanese Corporation, New York, N.Y., a corporation of Delaware Continuation-impart of application Ser. No. 325,254, Nov. 21, 1963. This application Aug. 23, 1967, Ser. No. 662,633

Int. Cl. B32b /12; D04h N46 US. Cl. 161-141 22 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This is a continuation-in-part of Ser. No. 325,254, filed Nov. 21, 1963, now abandoned.

This invention relates to the production of novel nonwoven needle punched batting material and more particularly to the production of a nonwoven needle punched material which contains both continuous filaments fibers and staple fibers.

Nonwoven needle punched batting materials have conventionally been produced from staple fibers. Such needle punched battings or felts are normally considered to be relatively strong and have good dimensional stability, particularly transverse to the machine direction. However, the strength and dimensional stability is directly related to the preponderant direction of the fibers and the amount of needle punching, with greater amounts of punching giving the higher tensile strengths and stability. However, the cost of needle punching greatly increases with the increased number of punches per square inch. Further, conventional staple batting has a preponderance of fibers lying perpendicular to the machine direction and therefore the strength in the machine direction remains substantially less than in the major fiber direction irrespective of the amount of needle punching. Therefore, it is highly desirable to obtain a batting material of increased tensile strength and stability in all directions, particularly with proportionately less needle punching.

It is an object of the present invention to provide a novel nonwoven batting material made from continuous filament fibers having a tensile assymetry approaching 1:1. It is another object of the present invention to provide a method for increasing the tensile strength and dimensional stability of nonwoven battings without increasing the requirements for needle punching. It is a further object of the present invention to provide a batting material particularly useful for carpeting, blankets, poromeric substrate materials and the like high performance batting materials. These and other objects will become apparent to those skilled in the art from a description of the invention which follows.

SUMMARY OF THE INVENTION In accordance with the invention, a method for producing a nonwoven batting is provided comprising forming a web of continuous crimped deregistered filaments by laterally spreading the tow of said deregistered filaments to form a first fibrous layer, placing a second layer of nonwoven fibrous material in contact with said first layer and needle punching the fibers, thereby intimately entangling the fibrous layers. More specifically, a preferred embodiment involves utilizing staple fibers in contact with at least one side of the continuous filament web and needle punching to obtain the nonwoven batting. When both fibrous materials are continuous filament webs, it is preferred that the fibers of the webs are of a tenacity below about 2 grams per denier at which tenacities the fibers tend to break into staple during the needling operation.

The present invention provides a method whereby continuous filaments in the form of a crimped deregistered spread web are incorporated into a nonwoven batting to provide a product of increased tensile strength and dimensional stability at a lower cost. The novel nonwoven product of the present invention can be made either entirely of continuous filament material or as is most preferred, a combination of continuous filament and staple fibers.

The invention will be more fully described by reference to the drawings wherein:

FIG. 1 is a schematic illustrating a process for deregistering and subsequently opening a tow by spreading the tow laterally to form a lightweight web;

FIG. 2 is a schematic illustrating a method for contacting one or more lightweight continuous filament webs with one or more card webs of staple fibers and needling the webs to produce the needled batting of the present invention; and

FIG. 3 is a schematic illustrating another method of the present invention for forming a cross lapped batting of lightweight continuous filament web and contacting the cross lapped batting with one or more cards of staple fibers and needling the combined fibers into the needled batting of the present invention.

Referring more particularly to FIG. 1, a band of crimped continuous filament tow 10.is drawn from bale 12 through a banding jet 13 comprising a stationary cylinder 14, having a slit running lengthwise of the cylinder at its highest point, and a curved baffie member 16 parallel to, and spaced about the thickness of the tow 10, from the adjacent surface of said cylinder, so that the tow band 10 passes between said bafiie mem ber 16 and cylinder 14. Air under pressure is supplied to the interior of cylinder 14 and emerges as a stream from the slit of said cylinder, the slit being cut at an angle such that the air stream has a component in a direction opposing the forward motion of the stream. The air jet preconditions the tow for further processing by removing snags, false twists, straightens and flattens the tow and, if desired, spreads the tow somewhat to provide a uniform thickness.

Tow band 10 is hence passed around stationary tensioning bars 17 and 18 to help smooth and uniformly pretension the band, said bars being adjustably mounted, so that their angle to the horizontal may be varied, to adjust the position of the band on subsequent processing equipment with which the band comes into contact downstream of the bars.

After leaving bars 17 and 18 the band passes into the tow opening zone. The tow may be conveniently opened or deregistered, to prepare it for one or more spreading stages by subjecting it while moving in a predetermined path, to a differential gripping action between a plurality of points spaced from one another both longitudinally and transversely in the path so that certain laterally spaced sections of the tow are positively gripped relative to other lateral space sections of the tow, alternating with the grip sections, which are not gripped at all or are gripped at different relative points. In this manner there is produced a relative shifting of the adjacent filaments longitudinally along the tow whereby the crimps are moved out of registry with one another. The shifting action is a function of the differential positive gripping of the tow. Preferably, although not necessarily, the differential gripping action is such that a relative lateral displacement between adjacent filaments of the tow is also effected, so that the combination of two transverse filament movements brings about the complete opening of the tow.

Several methods for effecting the differential gripping action are known in the art as well as several different apparatuses for effecting the differential gripping, which apparatuses deregister the tow with varying degrees of success. A preferred apparatus is disclosed in the aforementioned Dunlap et al. patent US. 3,156,016.

Typically, the differential gripping action is achieved by using at least one pair of rollers, one of which is smooth surfaced and the other of which is patterned over its entire periphery. The most preferred apparatus comprises a plurality of such pair of rollers arranged in tandem wherein one of each pair of rollers comprises a smooth surfaced roll coated with a resilient material such as rubber, and the other roller has alternating lands and grooves. Preferably, the lands and grooves form helical threads of about 8 to 20 per inch.

Thus, the tow is passed through the nip of a pair of rolls 19 and 21 prior to being passed through a second pair of rolls 22 and 23. In the most preferred embodiment, rolls 19 and 23 are the patterned rolls, such as threaded steel rolls and rolls 21 and 22 are resilient surfaced rolls.

Each pair of rolls is individually driven at a predetermined controlled speed. Generally, only one roll of each pair is positively driven while the other is in yieldable compressive contact with the driven roll and rotates due to the passing of the tow between the rollers. The differential gripping and deregistering action is produced by driving the second pair of rollers at a faster rate of speed than the first pair. Thus, the second pair of rollers is typically driven at a rate of about 1.1 to about 8 times, and more preferably, at a rate of about 1.2 to about 3 times that of the first pair.

On leaving the deregistration zone, the crimp in the tow is out of registry with adjacent filaments.

After deregistering the tow, the tow is subjected to one or more spreading stages. Various spreading means can be used to spread the deregistered tow into a uniform web. Such means include mechanical spreading bars, diverging belts, air jets and the like. The most preferred means is the air jet, also known as a banding jet. Therefore the invention will be described more particularly with reference to air spreaders although it is to be understood that other types of spreaders can be used with correspondingly good results.

The tow is spread as shown in FIG. 1 by means of a first spreader 24. The tow is pulled through spreader 24 by the action of driven rollers 36 and 37 about which tow is S wrapped. In passing through spreader 24, the tow is spread about 2 to 4 times the width of the tow exiting from the deregistration zone. As is preferred in the present invention, the tow is preferaby again spread, such as in second spreader 38 wherein the spread band is again spread 2 to about 4 times the width of the web drawn through rollers 36 and 37. Again, the web is drawn through spreader 38 by means of another set of driven rollers 39 and 41. Thus, the spreading action preferably spreads the tow into a web at least twice the original width of the tow and more preferably 2 to about 10 times the original tow width to produce a web of less than 1 ounce per square yard and more preferably about 0.005 to 0.5 ounce per square yard and most preferably about 0.01 to 0.25 ounce per square yard.

From rolls 39 and 41, the tow falls in a freely hanging shallow catenary 42 onto a horizontal moving surface of a wide, endless belt 43. Idler roll 44, mounted on lever arms 46 pivoted at 47, extends across the full width of the web on belt 43. The idler roll serves to bring the tow web into firm contact with belt 43 to define the shape and position of catenary 42 and also to keep any loose ends in the catenary portion from being drawn around roll 41. Catenary 42 also serves to relax the spread web which relaxation partially restores crimping which was stretched during the deregistration and spreading operation. The relaxation by passing through a catenary further serves as a self healing process by removing striations which may have formed during the spreading operation. A static bar (not shown) is preferably maintained in close proximity with catenary 42 to remove static electricity from the spread web.

Referring more particularly to FIG. 2, a spread continuous web 50, which can be the single layer web produced in accordance with FIG. 1 or a plurality of such webs laid one over the other, is conveniently contacted with a batting of a carded staple fibers 52 and 54 thereby sandwiching the continuous filament web between the layers of staple fibers to form a core therefor. The combined fibers are drawn from lay-up belt 56 by means of nip rollers 57 and 58 and fed to needle puncher 60 wherein the fibers are needled to intimately combine them into an integrated batting. Needle puncher 60 preferably needles the fibrous material in an amount of about 1,000 to 5,000 or more punches per square inch and more preferably about 2,000 to 4,000 punches per square inch. The punching is effected by the passage of the sandwiched batting through the needle puncher one or more times, depending on the intensity of punching with each pass.

FIG. 3 illustrates another method of contacting staple fibers with continuous filament fibers prior to needle punching. In addition, FIG. 3 illustrates a preferred method for positioning a web of continuous filaments prior to needle punching with or without staple fibers. Again, a spread web 50 of continuous filaments is fed to an endless conveying belt running at an acute angle of about 15 to degrees from collecting belt 62. The speed of feed belt 64 and collecting belt 62 is cooperatively adjusted to control the angle of layering web 50 on belt 62 and the thickness or number of layers of web cross lapped. Feed belt 64 can reciprocally pass over collecting belt 62 to aid in laying the web in the desired manner. It will be noted that when feed belt 64 is operated at-a rate faster than collecting belt 62, the thickness of the cross lapped web 66 is correspondingly increased. While cross lapped continuous filament web 66 can be needle punched as is to form an intimately entangled fiber batting, it is more preferable to feed at least one and preferably two additional layers of either continuous filament webs or staple batting 68 and 70 above and below cross lapped web 66 prior to needle punching, thereby increasing the dimensional stability of the produced batting in the machine direction. Most preferably, webs 68 and 70 are battings of staple fibers which are contacted with a cross lapped web 66 and subsequently needle punched to form the intimately entangled batting material of the present invention.

The needle punched batting can be impregnated with a polymeric material to increase the tensile strength, enhance the physical characteristics, control moisture permeability and the like as may be desired. Such bonding can be effected either with or without calendaring as may be desired for the particular end use. For instance, when the product is to be used as a blanket, calendering may be undesirable. However, for use as a carpet or a carpeting substrate, a poromeric material or the like, various bonding agents are preferably used to impregnate the needled batting with about 30 to percent polymer based on the weight of the batting with subsequent calendering being preferred.

The present invention is useful with all continuous filament materials which have been crimped prior to deregistration. The same materials can be used for the staple as well as conventional staple materials such as cotton, wool, asbestos, etc. The continuous filament web producing process is particularly useful with filaments of polyethylene terephthalate polyester and cellulose acetate of the usual acetyl content of about 54 to 55 percent calculated as acetic acid. However, the invention is also equally applicable to other tows such as those made of other polyesters such as polyesters of 70/30 isophthalic and terephthalic acids and other glycols such as dimethylolcyclohexane; linear super polyamides such as nylon 6 and nylon 66; polyacrylonitrile and copolymers of acrylonitrile; olefinic polymers and copolymers such as isotactic polypropylene; other organic derivatives of cellulose such as esters and/or ethers of cellulose, for example cellulose propionate and cellulose acetate propionate and the like; highly esterified cellulose containing less than 0.29 free hydroxyl groups per anhydroglucose units such as cellulose triacetate; rayon and the like.

As previously noted in the manufacture of needled battings made entirely of continuous filament webs, the tenacity of the fibers is preferably less than about 2 grams per denier so as to be more readily processed during needle punching. Acetate fibers are particularly desirable for this use.

The number of filaments in the starting tow can vary within wide limits and may range up to as high as about one million with a denier per filament as high as about 25, that is, in the range of about 0.5 to about 25 and more preferably in the range of 1 to 20 denier per filament. The number of crimps per inch of tow may range up to as high as about 80, but for most end products a crimp of about 3 to 50 crimps per inch, preferably about 3 to 20 crimps per inch of starting tow are found to be exceptionally satisfactory.

The carded staple used in the present invention is produced in accordance with conventional staple batting formation processes. The staple can be of the same material as the continuous filament web or for particularly desirable etfects of another material such as wool or cotton.

The invention will be described more fully by reference to the examples which show certain preferred embodiments of the present invention.

EXAMPLE 1 A lightweight web was made in accordance with FIG. 1 by deregistering and spreading a band of crimped cellulose acetate tow having a total denier of 42,000 and made up of 3 denier continuous filaments of cellulose acetate. The filaments were crimped at a rate of 8 /2 crimps per inch. The tow band was drawn from a bale through a banding jet and pretensioning bars prior to being fed to a deregistration zone comprising two pairs of rollers in tandem. In the deregistration zone the tow was fed into the nip of a pair of rollers, one which was a rubber surface roller and the other a helically grooved steel roller having 14 turns per inch, out about ,5 inch deep. The rollers were in pressure contact with each other. The first pair of rolls was driven at a peripheral speed of about 45 feet per minute. From the first pair of rollers, the band was passed horizontally to the nip of the second pair of rollers corresponding to the first pair, which second pair was driven at a peripheral speed of 66 feet per minute. The tow exiting from the deregistration zone was about 8 inches wide.

From the deregistration zone, the deregistered tow was passed into a first air spreader which had a passage for the tow 24 inches in width and inch between the confining walls. The air spreader was supplied with air under a constant pressure of about 4 pounds per square inch.

In passing through the first air spreader, the tow band was diverged uniformly from its 8 inch width to the full 24 inch width of the air spreader. From the first air spreader, the tow was drawn by means of drive rollers operated at a peripheral speed of 44 feet per minute which served the additional function of also holding the tow in the spread state.

The tow was then fed to a second air spreader of the same design as the first air spreader with the exception that it was 50 inches in width. The second air spreader was operated under the same air pressure as the first air spreader. In passing through the second air spreader, the tow was again spread uniformly to the full 50 inch width of the second spreader. The 50 inch width was maintained by drawing the tow through the spreader by means of another pair of drive rollers driven at a peripheral speed of 42 feet per minute. The lightweight web was then dropped freely to form a hanging shallow catenary onto the horizontal moving surface of a wide endless belt operated at a speed of 46 feet per minute. The catenary drop relaxed the spread web, partially restored lost crimps and removed striations. The web retained substantially its 50inch width. The produced web was about 50 inches in width and was of a weight of 6.01 grams per square yard.

The produced web is then cross lapped in accordance with FIG. 3 to form a batting having a weight of about 15 ounces per square yard. The resulting batting is then passed without staple fibers through a conventional needle punching machine in which the batting is subjected to a series of rapidly reciprocating needles perpendicular to the face of the batting thereby bringing the fibers of the adjacent cross lapped layers into an intimately entangled unitarian matt. The batting is passed through the needling zone until a total of 1,500 punches per square inch have been made from each side of the batting.

Comparison of this needled batting with a needled batting made from the same weight of the same filaments, but in which the filaments had been cut to staple from and made into card webs before cross-laying, shows that the needled batting made from the spread Webs has a much softer drape and conforms more readily to the shape of any body on which it is placed.

EXAMPLE 2 In the same manner as Example 1, the spread cellulose acetate web produced therein is cross lapped in accordance with FIG. 3, utilizing a batting of polyethylene terephthalate staple fibers above and below the cross lapped continuous filament thereby sandwiching the continuous filament cross lapped material between the staple fibers. The sandwiched material is then fed to a needle punch in accordance with Example 1. The battings of staple fibers are both of a density of about 5 ounces per square yard and the cross lapped continuous filament is cross lapped to yield a batting of about 5 ounces per square yard. The intimately entangled fibers withdraws from the needle punching have a total density of about 15 ounces per square yard. Again, the needle punching is effected to produce a total of about 3,000 punches, with about 1,500 punches per square inch on each surface.

Comparison of the produced needle punched batting with a batting produced entirely from staple of a similar acetate-polyester composition readily illustrates the increased tensile strength in all directions of the batting of the present invention over that of the old staple fibers. The staple fiber batting is of good tensile strength in the machine direction but is greatly reduced in tensile strength in the directions perpendicular to the machine direction. The batting of the present invention has a tensile assymetry approaching 1:1, that is, the tensile strength in both directions is about equal.

In the same manner, rather than utilizing card staple to sandwich the cross lapped continuous filament, a spread web of aceate continuous filament fibers is laid above and below the cross lapped web prior to needling thereby producing a needled web of correspondingly improved properties, particularly in hand and drape.

EXAMPLE 3 A tow of polyethylene terephthalate continuous filament fibers is spread in accordance with Example 1 to produce a lightweight web having a density of about 8 grams per square yard. The spread web is then layered with the one web upon another to increase the batting weight to about 2 ounces per square yard. The produced batting is then layered with a 4 ounce per square yard batting of carded Wool staple both above and below the continuous filament web. The resulting sandwiched batting is then needle punched to a total of about 2,500 punches per square inch. The resulting product is particularly suitable for blankets, insulating garments and the like.

EXAMPLE 4 A substrate particularly suitable for poromeric use is made in accordance with the present invention by spreading a tow of polyethylene terephthalate continuous filament fibers into a web of about 0.5 ounce per square yard as described in Example l. The polyester tow is of 1.5 denier per filament.

The spread web is then cross lapped in accordance with FIG. 3 to produce a cross lapped web of about 3 ounces per square yard. A batting of 1.8 denier per filament 1.5 inch drawn polypropylene staple fiber is positioned on both sides of the polyester web thereby sandwiching the polyester between the polypropylene batting. The sandwiched batting is then needle punched to about 4,000 punches per square inch. The needled batting is about 6 ounces per square yard. The batting is then shrunk about 35 percent in area and impregnated with a polyurethane latex binding agent at a 50 percent weight by solids pickup based on the dry fiber weight. The batting is then calendered and sueded to produce a substrate which is further coated with a polymeric elastorner to produce a porornatic material.

While there have been described various embodiments of the present invention, the method described is not intended to be understood as limiting the scope of the invention as it is realized that changes therein are possible. It is intended that each element recited in the following claims is to be understood as referring to all equivalent elements for accomplishing substantially the same results in substantially the same or equivalent manner. It is intended to cover the invention broadly in whatever form its principles may be utilized.

What is claimed is:

1. A method for producing a nonwoven batting comprising forrning a web of continuous crimped deregistered filaments by laterally spreading a tow of said deregistered filaments to form a first fibrous layer, placing a second layer of nonwoven fibrous material in contact with said first layer and needle punching the fibers by subjecting the same to a series of rapidly reciprocating needles thereby intimately entangling the fibrous layers.

2. The method of claim 1 wherein the second layer of nonwoven fibrous material is a web of continuous crimped deregistered filaments.

3. The method of claim 2 wherein the continuous filament is cellulose acetate.

4. The method of claim 3 wherein the continuous filament web is cross lapped to form a batting prior to needle punching.

5. The method of claim 1 wherein the second layer of nonwoven fibrous material is staple fibers.

6. The method of claim 5 wherein the staple fibers are placed on both sides of the continuous filament web prior to needling.

7. The method of claim 1 wherein the continuous filament spread tow is cross lapped prior to needle punching.

8. The method of claim 1 wherein the tow is cellulose acetate.

9. The method of claim 1 wherein the tow is polyethylene terephthalate.

10. The method of claim 1 wherein the tow is deregistered by subjecting the crimped continuous filaments to a differential gripping action wherein the individual filaments are alternately gripped and released as they are moved through a deregistering zone.

11. The method of claim 1 wherein the deregistered web of continuous filaments comprises a plurality of web layers.

12. The method of claim 1 wherein the fibers are punched with about 1,000 to 5,000 punches per square inch.

13. The method of claim 1 wherein the needled batting is impregnated with a bonding agent.

14. The method of claim 1 wherein a layer of staple fibers is placed on both sides of said continuous filament, said continuous filament being cross lapped and subsequently the combined fibrous materials are needle punched with about 1,000 to 5,000 punches per square inch.

15. A fibrous batting material comprising a deregistered spread web of continuous filaments layered with a second fibrous material, said web and said second fibrous material being needle punched into an intimately entangled fibrous batting by subjecting the same to a series of rapidly reciprocating needles.

16. The batting of claim 15 wherein the second fibrous material is a continuous filament web and wherein both webs are of a filamentary tenacity of less than about 2 grams per denier.

17. The batting of claim 15 wherein the second fibrous material is staple fibers.

18. The batting of claim 15 wherein the second fibrous material is staple fibers and said staple fibers are layered to both sides of said web.

19. The batting of claim 18 in the form of a blanket.

20. The batting of claim 15 wherein the fibrous material is needle punched with about 1,000 to 5,000 punches per square inch.

21. The batting of claim 15 wherein at least one of the fibrous materials is cellulose acetate.

22. The batting of claim 15 wherein at least one of the fibrous materials is polyethylene terephthalate.

References Cited UNITED STATES PATENTS 3,016,581 1/1962 Smith l965 3,071,783 l/1963 Gamble 5337 3,235,935 2/1966 Daruwalla 2872.2

3,383,273 5/1968 Pearson et al 16l-154 ROBERT F. BURNETT, Primary Examiner R. L. MAY, Assistant Examiner US. Cl. X.R.

19-65, 156-l48, 181; 16l-59, 143, I54, 156, 

